Is it possible to show the history on a detachable window?
Every action you've done is listed on the Info Window, you can view it if you pull it down.



The commands are listed in Python and list changes to your file as they are made. They're not editable, nor can you go back or undo form here.

For those of us whose language skills are limited to spoken languages and are code illiterate, the option is the Undo menu, accessed by pressing CtrlAltZ. 

It will display a list of steps you can undo. Note that the list cannot be kept open permanently.



Form the manual


  Rolling back actions using the Undo History feature will take you back to the action you choose. Much like how you can alternate between going backward in time with Ctrl-Z and then forward with Ctrl-Shift-Z, you can hop around on the Undo timeline as much as you want as long as you do not make a new change. Once you do make a new change, the Undo History is truncated at that point.


The number of undo steps is determined by this setting on the user preferences:



Depending on your system's RAM, you can set up to 256 undo steps.